What's the usual amount of gas usage in these trucks? I searched around the forums, but I keep seeing people saying they are getting 16 mpg, etc. I think the 16 mpg would be close to what I got on the freeway, but 8 mpg was combined city/highway driving. Is that about right? I don't really romp on it, and the computer was reset right before this tank of gas, so I have to assume it was probably running a little bit pig rich.

Does all of that sound about right?

 

You should be able to do better than that in around town driving..... Have you fixed your plenum yet?

 

Don't trust the computer, calculate it yourself.

 

The plenum is getting fixed next month, I'm probably getting 10 mpg city, and about 16 freeway, but combined it was about 8 mpg if I did the math right. 280 miles / 35 = 8 mpg. Did I do it wrong? Some people say put 2 or 3 gallons in it, drive it, then figure it out off of the 3 gallons since there is too many variables in the full tank.

Could the plenum leaking really cause that much of a drop in MPG? When I looked into the plenum it looked clean, but that doesn't mean it doesn't need changed still.

 

Plenum is a giant vacuum leak. So, yeah, it can indeed have an effect on fuel economy.

The trouble with doing the two or three gallon trick is...... you have to run it till it quits..... which is really bad for the fuel pump. Averaging your economy over the course of several tanks of gas will give you a better number. (more accurate, not necessarily higher. )

What about your O2 sensors? How old are them fellers? They have the biggest impact on fuel economy.

 

O2's will probably need changed. I checked with the scanner awhile back and they seem to range fine, but they are a little slow so I know they will need changed soon. Probably going to change them once I gut the cat, figure I'll have to yank the rear one out anyways to put in a spacer. Might as well do that all at the same time, lol.

 

and due to a plenum leak it can foul plugs, foul 02 sensors, and clog the cat....theres 4 things right there that all effect mpgs....

 

Well, it doesn't leak manifold pressure, so the plenum really isn't bad, but I know it's not a Hughes kit on there, so I am going to replace it anyways. I'm wondering if the plenum gaskets were replaced before and whoever did it didn't change the cat/O2/spark plugs after he did it. I guess it's probably about time to do all of the above anyways. I've only had the truck for about a month so I haven't had much time to dig into it yet, besides it's just my occasional hauler right now until the summer when it's time to see how stuck I can get it with only 2 wheel drive, lol.

 

It can't possibly be 10 city, 16 hgwy and also a combined 8, unless you know some form of math I don't! It would have to be between 10-16, the exact mpg would depend on the percentage of driving done city vs hgwy.

 

I wish I could get 8...